Multiple pressure control valve



May 30, 1967 w. RANKIN MULTIPLE PRESSURE CONTROL VALVE Filed June 9, 1964 7 a 0 %H 2 MMm Q I V v, w? w m /7 a i q k 3 M. Q E M \\\\\\\\\\\\\\/M A II. 1 a 4 EEK 4 A m w 5 w m m, K M m: WM m T. N G .ZVW fi D N? E A m w B R U Y- 2 T B G I b F M HIS ATTORNEY.

United States Patent 3,322,153 MULTIPLE PRESSURE CONTROL VALVE Andrew W. Rankin, Leominster, Mass, assignor to General Electric Company, a corporation of New York Fiied June 9, 1964, Ser. No. 373,680 6 Claims. (Cl. 137630.19)

ABSTRACT OF THE DISCLOSURE Steam turbine control valve chest with sequentially actuated valves therein has internal partition (29) dividing the chest into two chambers for simultaneous connection to two steam pressure sources and preferential operation from the low pressure source.

This invention relates to a valve mechanism for controlling the flow of elastic fluid from two or more sources at different pressures through a group of sequentiallyactuated control valves to a turbine.

It is often desirable to make provisions for supplying pressurized fluid to a turbine from more than one source. An example of this is found in the auxiliary turbine which drives the boiler feed pump for a large steam turbinegenerator powerplant. The heat balance may indicate that the boiler feed pump turbine should be connected to a particular extraction point for utilizing steam after it has been partially expanded in the main turbine to give the best cycle elficiency. At light loads on the main turbine, however, this extraction pressure becomes too low to supply adequate power to the auxiliary turbine, and it is necessary to supply the auxiliary turbine With steam from a hinger pressure source.

One means by which this problem has been solved in the past is by external valving arrangements which disconnect the turbine inlet from the low pressure steam source and reconnect it to a high pressure steam source. Another solution has been to employ on the turbine inlet a separate high pressure control valve casing with its own control valve and stop valve leading to a separate high pressure nozzle arc or admission nozzle ahead of the first stage of turbine blades. The first solution mentioned has the disadvantage that the auxiliary turbine experiences a thermal shock when the external valving switches from one steam source to the other, and some throttling of the higher-pressure source must be employed which introduces additional losses.

The second solution (i.e., using a small separate highpressure valve casing) is more expensive, and is less efficient when operating from the high pressure steam source, since the wheel speed, number of stages, and bucket heights of the auxiliary turbine have been designed for efficient operation in low-pressure steam. Accordingly, they do not give efiicient operation at the pressure ratio, etc., of the very high-pressure source of steam which is normally employed when using a separate high pressure valve casing.

Accordingly, one object of the present invention is to provide an improved control valve for automatically supplying steam to a turbine from either of two pressure sources as the need arises.

Another object of the invention is to provide an improved control valve casing with a group of valves for furnishing steam from more than one pressure source and where a number of valves are successively opened and closed on each pressure source for better efficiency.

Still another object of the invention is to provide an improved and less expensive control valve mechanism for supplying an auxiliary turbine in a steam power plant from a low pressure source for best cycle efficiency, and

Patented May 30, 1967 automatically connecting that auxiliary turbine to a higher pressure source when the low pressure is inadequate.

Yet another object of the invention is to provide an improved valve casing with a common actuator for sequentially opening and closing control valves, the casing being adapted for controlling steam from at least two sources to the nozzle arcs of a steam turbine.

Generally stated, the invention is practiced by providing a valve casing with two inlets and a partition dividing the interior easing into two chambers. A group of control valves is disposed in each of the chambers, and there is a common actuating mechanism for actuating the valves successively, first in one chamber and then in the other.

The subject matter of the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of practice, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which:

FIG. 1 is a transverse cross section taken through the valve and turbine casing, looking along the turbine axis toward the inlet end from the first stage of turbine blades, and

FIG. 2 is a schematic diagram of a steam turbine generator powerplant with a boiler feed pump turbine employing the valve casing of FIG. 1.

Referring now to FIG. 1 of the drawing, a control valve housing, shown generally as 1, is made as an integral part of the upper half 2 of the turbine casing, and connected to the lower half 3 of the casing by bolts 4. Supported from the walls of the casings 1, 2 is a nozzle box, shown generally as 5, and having side walls seen in cross section at 6, 7, and a top wall 8 dividing the interior of the valve housing 1 from the interior of the nozzle box 5.

Nozzle box 5 is made in the conventional manner with a number of interior dividing partitions such as 9, 10, 11, 12, 13 subdividing the nozzle box into passages 14, 15, 16, 17, 18, 19. Each of the passages 14 through 19 communicates with an arcuate discharge outlet, designated 20 through respectively. The outlets 20-25 are outfitted with admission nozzle blades (not shown) directed to discharge steam into the first stage turbine buckets at the proper angle in the conventional manner.

In accordance with the invention, the valve housing 1 has two separate inlets for steam at two dilferent pressures. The high pressure inlet 26 here is on the left side of housing 1, and low pressure inlet 27 is on the right side. Extending between a top wall 28 of the valve housing 1 and wall 8 is a partition 29 which separates the interior of the valve housing 1 into two separate chambers designated 30 and 31. Discharge openings 32, 33, 34, with suitable contoured valve seats, conduct steam from chamber 30 through passages 14, 15, 16 to nozzle arcs 20, 21, 22. Similarly, discharge openings 35, 36, 37 lead steam from chamber 31 to the nozzle arcs 23, 24, 25.

In order to control the flow of steam through discharge passages 32-34, there is a first group of valve disks 38, 39, actuated by valve stems 44-46 respectively. Similarly, cooperating with discharge openings 35-37 are valve disks 41-43 actuated by valve stems 47-49 respectively.

In accordance with the invention, a common actuator is disposed outside of valve housing 1 to operate valves 38-43 in sequence, first in the chamber 31 on the right side of partition 29 and then in the chamber 30 on the left side of partition 29. Any suitable common actuating means can be employed, but for simplicity of illustration, the method shown is a lift beam 50 raised and lowered by lift rods 51, 52 so as to successively contact abut- 3 men-ts, designated 53 through 58, located at different distances from the respective valve disks.

It will be observed from the foregoing that steam furnished to inlet 27 will be supplied to the turbine first as the valves open in the following order: 43, 42, 41. Then as the governing mechanism calls for more steam, the lift bar 50 will continue to rise and open valves in the following sequence on the other side of the partition; 40, 39, 38. The last mentioned valves supply steam from a high pressure source which is connected to inlet 26. Closing of the valves takes place in sequence in the reverse order so that discharge from chamber 30 is first blocked off and then discharge from chamber 31 is blocked off.

Reference to FIG. 2 of the drawing shows one application of the improved multiple pressure control valve casing to a boiler feed pump turbine, although many other applications are possible. A typical steam turbine powerplant includes a high pressure turbine 59, reheat turbine 60, and LP turbine 61 connected in tandem to drive a generator 62. Steam is reheated between turbines 59, 60 in a reheater 63 and after expansion in the reheat turbine 60 passes through a crossover conduit 64 to the LP turbine 61. The steam at the inlet to reheater 63 is at a higher pressure than that in the crossover conduit 64; however, the best over-all cycle efliciency indicates that an auxiliary turbine 65 driving a boiler feed pump 66 should be operated using steam from the crossover conduit 64. Hence the low pressure source at crossover conduit 64 is connected by means of a suitable conduit 67 through a one-way valve 68 to inlet 27 of valve casing 1 on the feed pump turbine.

In order to provide suflicient steam flow and pressure to drive the feed pump turbine when the main turbine powerplant is operating in light loads, an additional pipe 69 connects the reheater inlet steam to inlet 26 on the feed pump turbine. Partition 29 dividing these two pressure sources is indicated symbolically in FIG. 2. The reference numbers correspond to those used in FIG. 1 where they are duplicated.

The operation of the invention should be evident from the following description. During normal full load operation, steam is supplied from the LP crossover 64 to chamber 31 of the boiler feed pump turbine valve casing and valves 41-43 are opened and closed in sequence to control steam flow and give best efiiciency. At light loads when the steam pressure in the LP conduit 64 has dropped and there is inadequate steam pressure to properly ru n the boiler feed pump turbine, the common valve actuator 50 will continue to open as the feed pump governor requests more power. Valves 3840 now will be opened and closed in sequence to give good efliciency as high pressure steam is taken from pipe 69 and supplied to the nozzle arcs -22. When the boiler feed pump turbine 65 no longer requires the high pressure steam, conversion back to low pressure steam source is automatic as the actuator lift beam 50 lowers.

The arrangement shown is capable of many variations which do not depart from the scope of the invention. Al- 7 though the partition 29 is shown as dividing the valve housing 1 symmetrically, it is not necessary that the same number of valves be operated in the two inlet chambers, or that the partition be disposed symmetrically, or that only six valves he employed. Additional valves known as overload valves may be employed in either of the chambers to bypass steam around the first stage blades into the turbine shell. With overload valves of that type the auxiliary turbine can be operated at lower pressures than if overload valves are not used. Such overload valves do result in some loss of efiiciency, but this is accepted in order to operate at the lower inlet pressures. The arrangement may be used with any practical number of control valves in either chamber. FIGURE 1 shows the control valves to be of the bar-lift type with the lift beam outside the valve casing; this illustration has been chosen for simplicity of explanation. The invention also considers the control valves to be of the cam-lifted type, and FIG. 1 is not intended to restrict the invention to bar-lift'valves.

While there is shown herein what is considered to be the preferred embodiment of the invention, other modifications will occur to those skilled in the art, and it is desired to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A control valve assembly for controlling the flow of elastic fluid from more than one pressure source to a plurality of admission nozzles inside a turbine casing, comprising:

valve casing means defining at least first and second chambers having first and second inlets respectively and having respectively first and second groups of discharge outlets,

first and second groups of valves disposed in the first and second chambers respectively, each valve being arranged to control the flow of elastic fluid from a respective one of said outlets to a respective nozzle, and

common actuating means connected to lift each valve of the first valve group in sequence followed by each valve of the second group in sequence.

2. A control valve assembly for controlling flow of elastic fluid from two pressure sources to a plurality of admission nozzles inside a turbine casing comprising:

valve casing means defining firstand second chambers having first and second inlets respectively, each of said first and second chambers having a plurality of outlets,

a plurality of conduit means each adapted for connecting one of said outlets to one of said admission nozzles inside the turbine casing,

a first group of valves disposed in said first chamber, each valve of said group being arranged to control fluid flow from a respective one of the first chamber outlets,

a second group of valves disposed in the second chamber, each valve of the second group likewise controlling fluid flow from a respective one of the sec-' ond chamber outlets, common actuating means connected to actuate each valve of the first group in sequence followed by each valve of the second group in sequence. 7 3. A control valve assembly for controlling the flow of steam from high pressure and low pressure sources to a plurality of nozzle arcs supplying a stage of turbine blades disposed in a turbine casing, comprising:

valve casing means defining adjacent high pressure and low pressure chambers having high pressure and low pressure inlets respectively and also defining a first group of outlets from the high pressure chamber and a second group of outlets from the low pressure chamber, 7 a plurality of conduit means each adapted to connec one of said outlets to a respective nozzle are inside said turbine casing and upstream of said turbine blade stage,

a group of high pressure valves disposed in said high pressure chamber, each of said valves cooperating with one of said high pressure outlets,

a group of low pressure valves disposed in said low pressure chamber, each of said valves cooperating with one of said low pressure outlets, and

common valve actuating means arranged to lift successive low pressure valves followed by successive high pressure valves.

4. The combination according to claim 3, wherein said valve casing means comprises an elongated housing, wherein said high pressure and low pressure inlets are disposed at opposite ends thereof, and wherein the hous- 7 ing is divided into said high pressure and low pressure chambers by a partition between said inlets.

5. A control valve assembly for controlling flow of elastic fluid from two pressurized sources to a plurality of outlets comprising:

valve housing means comprising a single casing defining an elongated chamber having an inlet at either end thereof and divided into first and second inlet chambers by an internal partition between said inlets, said housing defining a plurality of outlets spaced along the lower Wall thereof on both sides of said partition,

a plurality of valves arranged in line, each of said valves being disposed to control the flow of fluid from a single one of said outlets, and

common valve actuating means including means for opening and closing said valves in sequence first on one side of said partition and then the other.

6. A valve mechanism for controlling the flow of fluid from two pressure sources to a plurality of outlets comprising:

a valve housing defining a chamber having first and second inlets thereto and including an internal partition disposed between said inlets to divide the chamber into first and second inlet chambers, said housing having a plurality of outlets leading from each of said first and second chambers,

a plurality of valves disposed in said first and second chambers, each of said valves being arranged to control the flow of fluid from a corresponding one of said outlets, and

common valve actuating means arranged to successively lift individual valves of the first and second chambers in sequence.

References Cited UNITED STATES PATENTS 15 822,673 6/1906 Keller 137--630.19X 2,192,193 3/1940 Johnson 137630.19 2,385,537 9/1945 Pentheny 137--630.19 2,713,351 7/1955 Van Nest 137630.19

20 CLARENCE R. GORDON, Primary Examiner. 

1. A CONTROL VALVE ASSEMBLY FOR CONTROLLING THE FLOW OF ELASTIC FLUID FROM MORE THAN ONE PRESSURE SOURCE TO A PLURALITY OF ADMISSION NOZZLES INSIDE A TURBINE CASING, COMPRISING; VALVE CASING MEANS DEFINING AT LEAST FIRST AND SECOND CHAMBERS HAVING FIRST AND SECOND INLETS RESPECTIVELY AND HAVING RESPECTIVELY FIRST AND SECOND GROUPS OF DISCHARGE OUTLETS, FIRST AND SECOND GROUPS OF VALVES DISPOSED IN THE FIRST AND SECOND CHAMBERS RESPECTIVELY, EACH VALVE BEING ARRANGED TO CONTROL THE FLOW OF ELASTIC FLUID FROM A RESPECTIVE ONE OF SAID OUTLETS TO A RESPECTIVE NOZZLE, AND COMMON ACTUATING MEANS CONNECTED TO LIFT EACH VALVE OF THE FIRST VALVE GROUP OF SEQUENCE FOLLOWED BY EACH VALVE OF THE SECOND GROUP IN SEQUENCE. 